Investigation of ion-acoustic compressive and rarefactive solitons in multicomponent plasma with negative ions

Propagation of ion-acoustic compressive (positive) and rarefactive (negative) solitons in a multicomponent plasma system consisting of positive and negative ions and electrons have been investigated. The Korteweg-de Vries (KdV) equation for a multicomponent plasma system has been considered. Then the Adomian decomposition method (ADM) has been applied to solve KdV equation and to obtain its soliton solution. Furthermore, the effect of parameters such as negative ion density (r) and velocity (ν) on the considered soliton is studied. Our obtained results show that in the fast mode of ion-acoustic soliton, there is a critical value of negative ions (r_c) below which the compressive solitons can exist and for value above that, the rarefactive solitons can be present. Both solitons will be defined through the KdV equation. Consequently, as density is a constant, the amplitude of the positive and negative solitons increases with an increase in velocity and the width of them decreases.